It is recognized that fuel for motorized vehicles, such as boats and cars, can be scarce and expensive. As a result, it is not uncommon for people to attempt to siphon the fuel stored in the fuel tanks of motorized vehicles.
Siphoning of fuel from a fuel tank generally involves placing a hose through the filler tube inlet or opening and down into the fuel held within the fuel tank. A suction pressure is then applied to the opposite end of the hose such that fuel within the tank flows upwardly and out of the tank through the hose.
There are a number of known solutions to address this problem. One is to provide locks or other securing devices to the cap of a filler pipe. However, this solution does not prevent siphoning once the lock or cap is broken. Another, in applications such as cars, provides a hinged access door that incorporates a lock. Such an access door can be defeated in a short period of time with a screw driver or a small pry bar causing serious damage to the vehicle body and paint. As a result, a car owner is not only subject to the cost of repurchasing fuel but also repairing the damage to the vehicle. Yet another is to provide a device that is inserted in to the filler tube at the entrance of the filler tube or at a position in close proximity to the entrance of the filler tube. Numerous patents are directed to these types of devices, including British Patent Specification 739,386, U.S. Published Application 2008/0156800, and U.S. Pat. Nos. 1,931,335; 2,107,600; 2,145,759; 2,147,755; 3,888,381; 3,920,145; 3,951,297; 4,326,641; 4,345,694; 4,630,748; 5,476,185; and 7,040,360. These types of devices are deficient because they can be defeated by inserting an elongated element like a rod in the fill tube and applying sufficient force to puncture, dislodge, or destroy these types of anti-siphoning devices. Some of these devices can also be considered deficient because they can obstruct or deter the flow of fuel through the fill tube causing fuel to back up or collect in the fill tube. This can cause an unacceptable increase in the amount of time required to fill a fuel tank or trigger a fuel nozzle with an automatic cut off to prematurely stop dispensing fuel. If a fuel nozzle does not include an automatic cut off, the fuel can spill outside the vehicle and cause environmental damage, subjecting the vehicle operator to significant fines. Even if a fuel nozzle does include an automatic cut off, an anti-siphon device that is at the entrance of the filler tube can still cause fuel spill when the fuel nozzle dispenses fuel at a high rate, such as boat applications. An anti-siphon device used in this circumstance will cause a backflow of fuel, which the fuel nozzle cannot prevent from leaving the tank. Some of these devices are also deficient in that they have limited application. Devices that are inserted at the entrance of the filler tube are generally not useful with fuel systems that incorporate threading on the interior of the filler tube for attaching a fuel cap because such inserts can interfere with the ability of the filler tube threading to interact with the cap. U.S. Pat. No. 4,345,694 purports to address some of these deficiencies by incorporating an elastomeric element that is pressed against the walls of the filler tube. However, such an element would not prevent an individual from gaining access to the device with a rod and applying sufficient force to defeat the elastomeric element. Further, the effectiveness of the device depends upon the person installing the device sufficiently compressing the elastomeric element during installation to insure that there is sufficient friction between the elastomeric element and the filler tube.
What is needed is an anti-siphoning device and fuel system that inhibits the ability of a thief to defeat the anti-siphoning device. It would be beneficial if such a device and system could inhibit the ability of a thief to identify and locate the anti-siphoning device. It would also be beneficial if such a device could be easily implemented in existing vehicles.